Radio frequency (RF) welding is a method for joining thin sheets of certain plastics with chemical dipoles together. Some of these plastic materials include thermoplastics such as polyvinylchloride (PVC), polyurethane (PU), thermoplastic polyurethane (TPU), thermoplastic elastomers (TPE), etc. The materials can be heated with high frequency electromagnetic waves. The method uses high frequency, usually between 13 and 120 MHz, electromagnetic energy to fuse the materials. As such, RF welding may also be known as high frequency (HF) welding or dielectric welding. Generally, a rapidly alternating electric field is set up between two metal welding plates or bars, where two pieces of the material are placed. The electric field causes the polar molecules found in the material to oscillate and orient themselves with respect to the field. The energy generated by this process causes a temperature increase (heat) which results in melting of the material. The welding plates or bars are then pressed together, forming a weld between the two pieces.
Because RF welding is better than conventional stitching used in constructing seams, RF welding has often been used to construct seams for various types of products, including clothing garments, bags, tents, etc., just to name a few examples. It is advantageous, therefore, to construct seams that are strong, air tight, and water tight.
However, the quality of welds or bonds formed by the RF welding process is usually a result of a complicated combination of machine parameters (power output, frequency), the temperature profile and bar pressure, and the material type and thickness. Achieving a strong and consistently leak-proof seal using RF welding can be difficult.
Therefore, it would be highly beneficial to provide systems and methods for seam construction that provide seams that are consistently strong, air tight, and water tight.